Manufacture of acid compositions



June 4; 1935. 1,l V- sHlNN Er AL. 2,003,907

MANUFAGTURE OF ACID COMPOSITIONS Filed Sept. 20, 1953 L1173/777 V. 5/1/'7171 Y BY T0711 60mm/J5 7n ATTORNEY Patented June 4, Y1935 Y Y UNITED PATENT OFFICE- maximums 20301; oomoslrrons l .T'olm V.\Shinn, Flushing, andA Tom Cummings, Br kl-yn, N.` Y., assignors to General Ghemi- `cal Company, New York, N., Y., a corporation of. New York. n I v Application September 20,1933', Serial No. 690MB' Y 15- Claims. GGLV 235-)f Y. A This invention relates to liquid mixtures designated by theformula NHlF'HF. For cerand/or compounds of hydrofluoric acidand amtain commercialprocesses, for example in frostmonia, `and more particularly the inventionis ing ,and etching glass, it is desirable to have directed to methods for making such products.' available mixtures and/or 'compounds contain- In some ci the arts,` for example in frosting inghydrofiuoric acid and ammonia, which mix- 5 glass; various compositions containing ingreditures or compounds are liquid at normal tements such as hydrouoric acid, ammonium biperatures. It is to the manufacture' ofsuch uoride and other ammonia compounds have products that the present invention is directed. been employed. The products made in accordi By the processes of the invention there may ance with the processes of the invention are be formed numerous liquid preferably anhydrous l0" particularly adapted forr use in similar operaproducts consisting of hydrouoric acid-amtions.; Y monia compositions of varying proportions of The Yprincipal objects of the present mvention hydrofluoric acid and' ammonia, 0r aqueous lie in the provision of methods forl making mixproducts CUmprShg hydroluoric acid-'ammonia tures and/or compounds of hydroiluoric acid COITIIJQSOIIS 0f Varying ratios of hydrofluoric. 15 and ammonia which mixtures and/or'compounds acid `to ammonia Yand having any desired conare liquids at normal temperatures; Another ob- CentfatiOIIS W-ih respect 130' the hYdrOUOrC ject of the invention is to provide methods` which acid-ammonia compositions up to thesubstanmay beeasily control-led toV produce" such liquid tially anhydrousV condition.

products' having various ratios of hydroiiuoric In accordance with the more desirablemeth- 20- aciu to ammonia. The invention also contemods of carrying' out the invention, hydrofluoric plates, asone of theimportant4 objects thereof, acidga's @Onttd With al1 ammOIla'Cil liquor, the provision of methods' by' Whichthe desired and preferably a liquor' containing hydrofiuoric products' `may be manufactured from readily acid-ammonia composition.V During the conavailab'le raw materials. It' `is not known tacting opmation,V the proportions of hydro- 25 whether the hydrofiuoric acid-ammonia prodluoric acid and ammonia are maintained such ucts'oi" the invention-are compoundsl or mixtures that hydroiiuoric acid is present in excess of or various combinations of both. `Vifha-tever may tlievamount required to combine with ammonia l be the case, for convenience; they liquid subto kform ammonmnr bi'luoride. Under thesecon- 0 stances formed by the methods ofthe invention ditions, a liquid composition of hydrofluoric acid 30 are designated herein asr hydrofluoric'acid-arn--l andammonia is obtained. Contacting the hymonia compositions. l drofiuoric acid gas andthe liquid may be con- When carrying out the; improved methods of veniently effected by passing the gas upwardly the invention', by bringing hydrouoric acid and and' owing 4the liquid stream downwardly ammonia, preferably ammonia containing Iiqthrough an absorbing tower, the gas and liquid 35 uids, together under conditions insuring the streams being so controlled that there is present presence of hydrofiuoric` acid inexcessl ofthe an excess of hydrofluoric acid over the a'nriountV amount oi hydroiiuori-c acid required to c'omneeded to combine with ammoniatoiorm ambine with ammonia toV produce ammonium'- bimonium bifluoride. In one modification of the n" fluoride; al composition coni-prising hydrouoric processes .constituting the invention, the con- 40 acid and ammonia is formed whichV is liquid tactinggoperation isregulated so that the amount at normal temperatures. j Y Y of hydroiiuorio acid gas absorbed bythe am- As'is known-when-hydrofiuoric acid and-ammonium uori'de Vliquid in one pass throughy moniavare associated, underV proper conditions, the tower is suchasV to form a liquid hydrodrofluoric acid and about 36 parts ``ammonia, desired hydrouoricacid-ammonia'ratio; VWhen that is, a weight ratioV of hydroiioric acid-to soV proceeding, the eiiluent liquid of the absorbammonia of 'F0' to 30l or about 2.33, ammonium ing tower isl ni-she'dproduct of a desired ratio, binuorid'eis ,formedwhich is a crystaliine sube., aboveaboutu 2.33; A portion of theliquid in proportions by weight oi" about '1G parts hyfiuoric acid-ammonia --composition having the 45 stance solid at normal temperatures, and usually is bledout of the system as productof the prjoc- 5.0`

ess, and to the remaining portion, ammonia, aqueous or anhydrous, dependent upon the nature of the product desired, is added, and such remaining portion is then returned to the absorbing tower. The amount of ammonia so added should be controlled so as to maintain the ratio above about 2.33, and to correspond with the quantity of hydrofluoric acid absorbed during the flow of a given amount of liquid through the tower so that the hydrouoric acid-ammonia ratio of the tower product is maintained substantially constant. l

In another modication of the process, the absorbing operation in the tower is so controlled that the liquid product thereof, although having a ratio above about 2.33, contains a greater proportion of hydrofluoric acid than does the desired hydrofluoric acid-ammonia composition. In this procedure, ammonia is addedto1a lportion of the tower product bled. oir from'the,

system, the amount of ammoniaadded beingl such as to offset the excess of hydrofluoric acid in the tower product and vprovidenin the finishedV product the desired hydrofluoric acid-ammonia ratio. The remaining portion of eiiiuent'liquid of the absorbing tower, after ,the -addition of ammonia, is again passed over the tower; Likewise in this instance,` the amount of ammonia added to the recycled liquid should be controlled so as to maintain ther'atio above about 2.33, but is suchv that the liquid product of the tower contains an excess of hydrofluoricacid overthe amount of hydrofluoric Aacid contained in the desired nished products,'the nalhydrouoric acid-ammonia ratio beingfadjusted vin 'a subsequent operation]v A' l,

Operating details, and further advantages and objects of the invention will beappreciated from a consideration of 'the following` description taken in connection with lthe accompanying drawing showing diagrammatically, in Figures l, 2 and 3, three types of apparatus which may be used to advantage inY carrying out the invention.

Referring toFig. 1, reference numeral AII) indicates a ygas main for introducing hydrouoric acid gas to the baseof an absorbing tower II. The-latter may be of any approved construction, and may comprise a vertically elongated cylindrical vessel having near Athe base a perforated plate I2 for supporting'a body of packing material represented at I3. The topof the tower is provided with a spray head I5 to facilitate distribution of liquid over packing. material I3. The liquid product formed in the tower runs through Va pipe connection I6 into a cooler yI'I from which overflow is withdrawnthrough pipeV i8. Aqueous or anhydrous ammonia, preferably in the form of gas, yis fed intocooler I'I at-the bottom through a pipe I9 controlled by a valve 2i. An air-lift 22 draws liquid from the bottom of cooler I'Ithrough a pipe23 and raises Vthe liquid to the sprayhead I5 'in the top ofthe absorbing tower.` f

Gases not absorbed in tower I I are discharged from the top, and. pass through a pipe l25into the base of a secondabsorbing tower 26. Exit gases from the top of absorber 26 flow through gas line 21 into thel'bottom of a thirdabsorb-1 ingY tower 28 from the top of which vunab'sorbed gases are conducted through conduit 29 into the Y lower endof 'an absorber 36. `Gases notv absorbed in the 'latter are dischargedffrorn the apparatusy through pipe 32.- The Vabsorbers 26 and 28 are of the same construction as towerl I.

Liquid is discharged from absorber 26 into a cooler 34, and liquids from absorber 28 run into a similar cooler 35. VAir-lifts 36 and 31 circulate liquid from coolers 34 and 35 over absorbers 26 and 28 respectively, the overflow of cooler 35 running through line 38 into the circulating system of tower 26. The aqueous hydrofluoric acid formed in absorbing towers 26 and 28 is withdrawn as overflow from cooler 34 through pipe 40.

Flow of gas through the absorbing towers from the hydrofluoric acid gas inlet I0 is inducedbyan air jet 2| in the gas outlet conduit 32 of the absorber 33. Water for absorbing hydrouoric acid gas passing through towers 26,

'28 and 30 is fed into the top of absorber 30 through a pipe 42, having a valve 43, and runs from the bottom of tower 38 into the top of absorber 28 through pipel MI. Tower 36 is packed and constructed similarly to absorbers 26 and 28,

except that there is no circulating system operated in conjunction with tower 36.

Referring to Fig. 2, absorber 45 isy similar to tower I I of Fig. 1.V The liquid product formed in absorber i5 is discharged from the base through connection Il into a cooler 48, while overflow from the latter runs through a pipe 50 into a Ysecond cooler 5I, from the top of'which the hydr'ouoric acidammonia product is withdrawn through pipe 53. Liquid from coolerJIS is recycled over tower'45 by means of pipe 55 and air-lift 56, as in Fig. l.' When operating with the apparatus of Fig.2, `final adjustment of the hydroi'luoric acid-ammonia ratio is made in cooler 5I, and for this purpose aqueous or anhydrous ammonia maybe run into cooler 5I throughpipe 5l controlled by valve 54. .The ammonia needed in the tower is introduced into the circulating system through a pipe 58 controlled by valve 59. The gas outlet conduit 25 at the top of absorber l5 is connected to the base of a second absorbing tower, corresponding to tower 26 of Fig.,1..

In Fig.`3 is illustrated an apparatus by whic aqueous hydrofluoric acid-ammonia compositions may be obtained by contacting hydrouoric acid gas with an vaqueous' liquid initially containing only ammonia. They hydrofluoric acid gas from thev inlet I6 passes in Vseries through the absorbers 68, 6I, 62 and 63 as in the apparatus of Fig. l. Each of the absorbers 68, 6I and 62 discharges into connecting coolers 55, 66 and 61, and. liquid from each-cooler is circulated over the associated absorbing tower` by air-lifts as in-Fig. l.. The overflow of cooler 6i is discharged through pipe 69 into the circulating sys-y tem of absorbing tower 6I, and the overflowA of cooler V65 similarly runs through pipe I6 into the circulating system ofthe first tower 60. The overilowy of cooler 65, discharged through pipe l'I, constitutes the product of the process.

vThe gases unabsorbed in tower 62 are. conducted by pipe 'I2 into the bottom of absorber 63 into the top of which water is fed through connection 113 controlled by valve I5. Exit gases of tower 63 are discharged from the apparatus through pipe 16. Aqueous ammonia is introduced into the top of absorbing tower 62 through a line 277 having a control valve 18, and the water fromY tower 63 runs-into the top of tower 62 through pipeV 79.

Mr )diiicationsof the process of the invention may beparried out in the different forms of apparatus describedl substantially as follows:

In all forms of apparatus, substantially anhydrouoricr acidgas,A obtained for example'bmzthe acidon calcium fluoride. is iedinto the base of )the `absorbing' towers H Q0 throughV `inlets Alll. In each system, the hydrouoricacidgasstream is,` caused to flowl atV a relatively-constant rate sumessivelyr through each V.seriesol absorbing towers :by the air jet `in gas `outlet-ofthe lesttower.. Y z d u Theimtention contempmtes therma'nufacture of mixtures or compounds. of hydroiluoric Aacid and ammonia which are atV normal temperatures. In .accordance with the '.invention, whenhydrouoric. acid gas `isf contacted .with ammoniacal liquid or' preferablyfwith a. liquid `containingn or comprising hydrouoric acid and ammonia, andzconditions are maintained such that hydrouoric acid is present during the. contactingv operation in amounts `iniexcess of the amount of the lsrydroiiutuicv aoidrequired to. combine with ammoniato .form ammonium bifluotemperatures, thereffislmaintained, ,during the process of manufacture, ari-excess of-hydroiluoric acid over that`V required to combine with ammonia.` to'form ammonium .bi-uoride; VSince hydrotiuoric acid andammonia. combine in apprcmimately` the weight ratio of '7D-to 30 to 4form the solid ammoniumbifluoride, inV the present A process, the presence of? hydrouoric acid `is maintained in excessof about 70% by weight.

In other `Words-in the-"operations of the invention, the ratio of hydroiiuoric acid to ammonia is preferabl-yfalways greater than '70 to 30, or in excessief about 2133;? i

It will be understood that products ofthe invention `may be 4madeof' aqueous or any concentrations uptd'the anhydrouscondition, Ainwhich latter case `the `productis Vliquid' and' Yconsists 'substantiall-y .ofl hydrofuoric-` acid and ammonia. Whatever may he the Aamount of the hydrouoric compositions of hydrouoric acid and ammonia,

are inexcessoiabout'213th` v M f `In the 'modiiications' o f apparatus of Figs. 1 and 2; aqueous or 'substantially anhydrous" hy'- drouoric acid-ammonia compositions of varying hydroiluori'c' vaci'd-azrrxmonia ratiosfmay be the hydroiluoric acid-ammonia ratios oi which convenientlymanufactored.` Y 1 Referring to Fig' 1, infstarting the operation, cool-erV lil is nlledwith-anaqueous solution of hydroiluoric acid, say of 60% strength. The

valvein air-lift 22 is opened 'sufficiently tocause circulation, Vat the desired rate, `of `liquidffrom cooler I1 over tower Il in a closed circuit `including` cooler t'l, pipe: Z3, distributor" l5, tower H and: pipel t6'. Upwardiflow 'ofi hydrolluoric acid gas through tower H is efrectedflby vjet 4l? in outtet-32 of absorber 30;. Valve 21|` in pipe" lil4 is opened, and` anhydrousziammoniar is. continuouslyrufed the.` coolerwl'l. Circulatiroffliquid mier the absorbing tower` fis main--` the circulating system is filled with substantially anhydrous hydrolluoric` acid-ammonia composition., Since.l at all times, `the proportions of hydroiluoricV acid` gas and ammonia are such that hydrouoric acid is present in excess of theV amount required 19o-combine with ammonia to form ammonium` bifiuoride, none of `the latter substance is produced, and the hydrouoric acidamm'oniacompositions are. in the liquid Vcondition.

In the' usual operation of the apparatus of li'ig. 1, -thef product-running out of the tower through: pipe IISV is in the finished condition, and has a hydroiiuoric acid-ammonia ratio in excess of about 2.33. By controlling the amount of ammonia introduced into the system through ,pipe I9 and by proper regulation of the circulating system, the liquid running out of the base .of t0wer-l=l through pipeY lfd has the desired hydroiiuoric acid-ammonia ratio, and a portion of such liquid overflows cooler Vi through pipe It and constitutes the product of the process. When operating so as to continuously produce in pipe i6 a liquid having a given hydroiluoric acidammonia ratidammonia is introduced into the bottomof cooler I`1in amount so that the liquor fed into thetop` ofthe tower'contains an excess of ammonia corresponding to the amount of hydroiluoricacid gas absorbed by the liquor during the subsequent' pass through the tower. Such amount is limited however, so that the ratio in theA recycled liquid is not reduced below ation-2.33.V

When itis desiredA to produce, Vin the apparatus of Fig. l, an aqueous liquid, the vhydroiluoric acid-ammonia ratio of" the hydrofluoric acidammonia composition contained in the liquid is adjusted as before by control of the amount of ammonia introduced intoftheapparatus through pipey i9; Similarly, the water content of the iinished products is Aregulated by water which may be admitted. to the system through pipe i9. When making a product whichis not anhydrous, aqueous ammonia may be employed and, introduced through pipe" i9. VVFurthermore, if conditions should require; both aqueous and anhydrous ammonia maybe introduced into the base of cooler' H. v

`Hydrofluoric acid gas unabsorbed in tower il flows through pipe 25 into the base of absorber 2t, and then successively through absorbers 25 and 37B. Water forabsorbing hydroiluoric acid ga's in tower 26, 28 andv 302 is introduced into the systen at the head ofV absorber 30 through pipe 42, and water from absorber 3l), containing relatively small quantities of absorbed hydrofiuoric acid,- runs by gravity through pipe M into the head'of absorber 28. VLiquidfrorn coolerV 35 is circulated through tower 28 by air-'lift 31, and the overflow? from cooler 35 runs through pipe 38 and thence overv tower 26. The amount ci water' fedfinto the system through'pipe [i2 and the circulating systems associated with towers vllf and 28 are preferably so regula-ted asto producean aqueous hydrofluoric acid oi 'about'60% concentration which" leaves cooler 34 Ythrough pipell.

In the operation of the apparatus of Fig. 2, the contacting operation in the'absorbing tower is so conducted that. the liquids leaving the base of the tower. through' pipe 41 rcontain hydrouoric acid in excess of the amount required to combine with ammonia to form the solid ammonium biiiuoride, and also in excess of the desired hydrofluoric acid-ammonia ratio of the nished product. ',The overflow of cooler 48 runs through. pipe 50 into cooler 5|, and since the liquid hydroluoric `acid-ammonia compositions running out of cooler 48 contain hydrouoric acid in excess of the desired hydrofluoric acid-ammonia'ratio of the finished product, the amounts of ammonia required to correctrthe hydrofluoric acid-ammonia ratioA are introduced into cooler 5l through pipe 51, the vquantity of ammonia being controlled by valve 54. The ammonia needed to maintainthe proper proportions of hydrofluoric acid and ammonia in absorbing tower 45, under any particular set Voi operating conditions,is fed into the circulating system through pipe 58. It will be understood that the amount of ammonia added to the crculating system during each'pass Aof a given amount of liquid doesrnot reduce the ratio in the recycled liquor below about 2.33, but is such that the liquid leaving thetowerthrough pipe 41 contains an excess of hydrofluoric acid over the desired ratio of; the nal product discharged from cooler 5|. v l

In the operation of the apparatus of Fig. 2, aqueous or substantially anhydrous products may be made. If the anhydrous product is desired, anhydrous ammoniais introduced into the system. On the other hand, if an aqueous product is desired, aqueous ammonia may be used in the circulating system,.or water and/or aqueous ammonia may` be added to the liquid in cooler 5I.

The apparatus of Fig. 3 may be employed to advantage inl situations where it is desired to obtain only aqueous hydrofluoric acid-ammonia compositions. -Aqueous ammonia is fed into the top of the tower 52, rather than nto absorber G3, in order to avoid possible 1osses of ammonia. The relatively small amount of kWater introduced into the absorber 63 through pipe v14, to insure absorption of substantially all rthe hydrouoric acid gas, together with the absorbed hydrofluoric acid runs into the top of tower 52. The water and aqueousV ammonia V thus rintroduced into tower 62- flowl through the.y absorbers and assooiated circulating systems countercurrent to the now of hydroiluoric acid gas introduced through inlet lil of tower 68, and aqueous products containing hydrofluoric acid-ammoniacompositions Y are discharged from the last cooler 65 l.through pipe 1l. In conducting operationsV in the apparatus of Fig. 3, it is to be understood that in the nal stages, sayin tower-60, conditionsl are such that there is maintained an excess of hydrouoric yacid over theamount of acid required to combine with ammonia` to form the solid ammonium bifluoride. Hence, whatever the water content of the productdisch'arged from thevapparatus through pipe1l Vmay be, thehydrofluoric acid-ammonia compositions contained therein are always in the liquid condition since the ratio of hydroiluoric acidto ammonia is in excess of 2.33.

The water 1 concentration. of fthe final products is dependentl upon f theamount of water introducedinto the system' either at `the'head of tower 63 or as a constituent of theaqueous ammonia Yfed Vinto tower. 62. Preferably, .the amount of water'run into tower 63' is only that sufcient toabsorb traces of hydrouoric acid gas which mayescape from towerA 62. .The hydrouoric acid-ammonia. ratio of the *aqueous productsv is 'controlled by the. amount ofV ammonia introduced through pipe 11. ffAt. some point in the apparatus,.possibly in tower 6| or the associated ciroulatingsystem, a hydrofluoric acid-ammonia ratio Vof about 2.33 is reached and ammonium. biuoride may tend .to crystallize out. Generally, the temperature rin fthe g system is high enough to prevent crystallization ofiammonium biiluoride "duringf the :relativelyv brief interval during which the hydrofluoric acid-'ammonia ratio isincreasing from. less thanfabout 2.33 to more; than 2.33.'.v If ammonium biluoride should tend to crystallize out, cooler 66 and the pipe connections` of-ithe vassociated :circulating system may beheated externally as may be required: to maintain in solution' ,ammoniumbifluoride which maymomentarily form. 1 The processes of the invention present numerous operating advantages. Hydrorluoric acidammonia compositions, liquid-at normal temper'atures, and having any desired hydrofluoric acid-ammonia ratio,rnay be produced. lSuch compositions may be anhydrous oraqueous as required, and liquid'products containing Varying amounts of water, may be conveniently made. Onerpreferredi commercially desirable substantially anhydrous` composition havinga hydroiluoric acid-ammonialratio ofv aboutv ,6.14` may Ybe manufactured without'diiculty, and the 4invention particularly lcontemplates vthe produc-I tiony of such a` product. Operatingfconditions may be readily controlled; Additionally, the processes lare such that the raw Amaterials employed, i. e., hydroiluoricacid gas'and-aqueQus and anhydrousarnmonia areV easily and cheaply obtainable. In the vappended claims, the term ammonia in the .expression calling for addition of ammonia to vthe vprocess v.liquors is intended to ,include hydrofluoric4 acid-ammonia solution having a ratio less than that of-the desired product. In all rnodications `of the invention, .when making aqueous; products, the liquor rintroduced into `the vtops -of towersv 1h45 and 60 may bea solutionv lor Aammoniumrbifluoridein water. Hence, in these instances, the hydroiluoric acid-ammonia ratio of the material in. solution may be about, and is not preferably less than2.'33. Y l.

l. The method Yof making a hydroiluoric acidammonia composition which comprises contacting hydrofluorick acid with a 'liquid containing hydrofluoric acidand ammonia in. ratio not: less than abouty 2.33 to.form a composition having a higher hydroiluoric acid-ammonia ratio, withdrawing a portion of said composition,v adding a `portionof said composition 1 adding. ammonia to a remaining .portion to.decreasezthe.hydro.-

fluoric acid-ammoniaratiol: to.` not ,substantially lessf'rthan that 'at-which .the composition is liq..

uid .at normal. temperatures,` and contacting the said remaining `portion with :further `quantities, of.hydrofluoricacid.;"1` f; 11 1I .11.41;

l 3;,The method oi makingafhydrouoric acidammonia composition which comprisescontacting .hydrofhu'iricm acid with a liquid containing hydrfluoriczacid and ammonia in ratio not less than about 2.33 to form a composition having a hydroiiuoric` acid-ammonia ratio of about 3.14,

withdrawing a portion of said composition, add-V ing ammonia to a remaining portion to decrease the hydrofluoric acid-ammonia ratio to not substantially less than about 2.33, and contacting said remaining portion with further quantities of hydrouoric acid to produce a composition having a hydrofluoric acid-ammonia ratio of about 6.14.

4. The method of making a hydroiiuoric acidammonia .composition which comprises contacthydroiiuoric acidand ammonia in ratio in eX- Y cess of about 2.33 to form a composition having a higher hydrofluoric acid-ammonia ratio, .withdrawing a portion of said composition, adding ammoniav thereto to decrease the hydrofluoric acid-ammonia ratio-ofk said composition, adding ammonia to the remaining portion Yto decrease thehydrofluoric acid-ammonia ratio to not substantially less than about 2.33, and contacting said remaining portion with further quantities' of hydroiiuoric acid."v

' 6.V The method of making'a hydrouoric acidammonia composition which comprises contacting hydroiiuoricA acid with an anhydrous liquid containing hydrofluoric acid and ammonia while maintaining a hydrofluoric` acid-ammonia ratio in excess of 2.33.

7. The method of making a hydrofluoric acidammonia composition which .comprises contacting hydroiiuoric acid with an'anhydrous'liquid containing hydroiluoric acid and ammonia, and maintaining hydrofluoric acid and ammonia present in such proportions asto form a hydroiiuoric acid-ammonia composition liquid at normal temperatures. l

8. The method of making a hydrofluoric acidammonia composition which comprises contacting hydroiiuoric acid with an anhydrous liquid containing hydrouoric acid-ammonia composition liquid at normal temperatures.

9. The method of making a hydrouoric acidammonia, and regulating the proportions of hy-` drofluoric acid and ammonia at the point of first contact of gas with liquid so as toform a hydroiiuoricJ-acid-ammonia composition'. liquid at normal temp'eraturesf.- fr: f. v102 The `method ior. maki'ng afsubstantially va'nhydrou's `hydroiiuoricacid-ammonia composition" which comprises@- contacting Vsubstantially F 'anhydrous hydrofluoricacidwith a substantiallyf. anhydrous 4material containing "hydrofluoric acidi! and ammonia-in Aratio Asuch that the materialii-isvliquid at normal temperatures to form al substantially anhydrous'-coinpositionvhaving a higher?" hydro'iiu'or'ic` acid-ammonia ratio,v withdrawing aportion of said composition"-V adding substantially anhydrous ammonia to a remaining portion to decrease the hydroiiuoric acid-v ammonia ratio to not substantially less than that at which the composition is liquid at normal temperatures, and contacting the said re- `maining portion with further quantities of sub' i withdrawing liquid product from the contact zone, continuously returning yto the contact zone a stream of the liquid product and adding to the liquid returned lammonia in amount to decrease the hydroi'luoric .acid-ammonia ratio to not less than about 2.33, 'and sufficient to maintain the predetermined hydrofluoric acidammonia ratio at the outlet of the contact zone. l

12. The method of continuously making a substantially anhydroush'ydrofluoric acid-ammonia composition which `comprises passing through a contact zone at a relatively constant Vrate a stream of hydroiiuoric acid gas, passing through the contact zone countercurrent to the ow of hydrouoric acid gas a stream of substantially anhydrous hydrofluoric acid-ammonia composition havingV a hydroluoric acid-ammonia ratio less than about A6.14 butin excess of about 2.33, regulating the amount of hydrofluoric acid absorbed torform a liquid composition having a hydroiiuoric acid-ammonia ratio of about 6.14, continuously withdrawing liquid hydrofluoric acid-ammonia composition from the contact `zone, continuously returning to the contact zone at the outlet of the contact zone.

13. The method of making a hydrofluoric acid-ammonia composition which comprises passing Vthrough a contact zone aY stream of hyrdroiiuoric acid gas, passing through the contact zone countercurrent to the flow of hydrouoric acid gas a liquid containing hydrouoric acidammonia composition, regulating the amount `of hydroiiuoric acidgas absorbed during passage of the liquid through the contact zone so as to forni a hydrofluoric acid-ammonia composition having a hydrouoric acid-ammonia ratio higher than the desired ratio of finished product, withand ammonia While maintaining a hydrouoric acid-ammonia ratio-in excess of 2.33;

15. The method of making aY substantially anhydrous hydrofluoric acid-ammonia composition which comprises contacting substantially anhydrous hydroluoric acid with a substantially anhydrous liquid containing hydrofluoric acidammonia composition liquid at normal temperatures.

JOHN V. SHINN. TOM CUMMINGS. 

